The invention provides for a specially designed, but simply structured, easy to assemble, labour and time saving, low-cost, plug-in assembly type of power supply unit.
A review of conventional power supply units will give the fact that the connection of components such as winding coil for the transformer thereof, with others such as power input, and the control circuit board is unexceptionally achieved by soldering of leads. That the transformer is soldered to external elements by leads will call for a lot of labour and time, and it is not compatible for automatic production. To account for the assembly processing in the conventional mode, the circuit board will have to be soldered to the output terminal of the transformer before the lead from the input end of the transformer is soldered to the power plugs on the bottom lid. While the input lead of the transformer is being soldered, the transformer, circuit board and outgoing wire from the power supply are all trailing behind in a very limited space where lead positioning and soldering will have to be done all at once. That is quite an inconvenience indeed, in addition, as the soldering progresses, refuse projections and remains of metallic residues will be left in the frame case to produce hidden incidents such as shorts or unwanted signals that will have a very strong negative effect on the next stage of instrument or implement. In addition, in cases where a high temperature soldering gun is used, damage will be easily done to the plastic housing case by careless operation. These will all contribute to a high rate of failure or rejections due to poor workmanship in the assembly procedure, causing trouble for the quality control inspectors and an increase in production costs.